A pocket full of jingling bottle caps...
- Thread starter cshontz
- Start date
MuckSavage
Adventurer
Belive me, I'm just a backyard wrench, but that sounds like Piston slap or bad main bearing(s) to me. But, you said oil pressure's good, so that might eliminate the bearing theory. My '96 4.0 has made a similar noise, REAL bad when you first start it, quiets down to a tap while running. It started doing this at around 130k miles, it now has 188k and no change. Aside from the noise, it runs great.
BUT, since I like your Cherokee so much, I think you should give it to me right away, and save yourself the trouble!:sombrero:
BUT, since I like your Cherokee so much, I think you should give it to me right away, and save yourself the trouble!:sombrero:
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Jim K in PA
Adventurer
I agree with the Jersey boy 
That sounds like bottom end, not valve train. It actually sounds more like a rod bearing, not a main. A loose main will affect oil pressure more than a loose rod bearing. Bearing failures on 4.0s are not as common as piston failures, but it happens. Did you mechanically over-rev it recently? Honestly, if you treat it nicely, it will probably run fine for another 100k with that noise. Damned things are indestructable. I have seen one keep running with two broken connecting rods.
That sounds like bottom end, not valve train. It actually sounds more like a rod bearing, not a main. A loose main will affect oil pressure more than a loose rod bearing. Bearing failures on 4.0s are not as common as piston failures, but it happens. Did you mechanically over-rev it recently? Honestly, if you treat it nicely, it will probably run fine for another 100k with that noise. Damned things are indestructable. I have seen one keep running with two broken connecting rods.
OverlandZJ
Expedition Leader
I'd drain the oil looking for particles, if any evidence pull the oilpan. I'd suspect a broken piston skirt.
My wife's WJ had a broken skirt, sounded similar and maintained good oil pressure.
My wife's WJ had a broken skirt, sounded similar and maintained good oil pressure.
Jim K in PA
Adventurer
Worth checking this out. If it did break a skirt, the cylinder bore can/will get gouged bad enough to render the block useless. A friend had one crack in his ZJ, and in less than 100 miles it scored the wall deep enough that it could not be sleeved.
BEST way to check is pulling the oil pan.
cshontz
Supporting Sponsor
Great feedback, gang. Regarding the diesel noise, I'm just going to keep an eye on it. Maybe this spring have the shop look at it, unless I feel it's becoming worse.
Regarding the jingling bottle caps, I've noticed this becomes more prevalent after the Cherokee has been driven for a while. Engine gets hot, oil becomes less viscous at higher temperatures, so I have a feeling some 40 weight will go a long way in helping this - what I presume to be lifter noise.
Regarding the jingling bottle caps, I've noticed this becomes more prevalent after the Cherokee has been driven for a while. Engine gets hot, oil becomes less viscous at higher temperatures, so I have a feeling some 40 weight will go a long way in helping this - what I presume to be lifter noise.